The present invention concerns a driving and control mechanism for a device for clamping, holding and presenting weft threads in gripper weaving looms. The mechanism is designed to move thread presentation elements, such as thread clamps or thread eyelets to various positions in relationship to the shed.
According to a preferred embodiment, the invention concerns a driving and control mechanism, that is particularly suitable for driving and controlling thread clamps. The thread clamps are able to take three positions as described in detail in U.S. patent application Ser. No. 033,739 of the applicant. This application describes a method for weaving without waste on the weft insertion side whereby, in a first position, such a thread clamp is in motionless condition; in a second position the thread clamp is presented in such a way that the clamped thread is brought into the path of a gripper and, whereby, in a third position, the clamp is positioned near the cloth edge in such a way that the weft thread introduced into the shed by means of the beating movement of the reed is pushed back into the clamp.
The present invention concerns a driving and control mechanism for such clamps, whereby during two successive cycles of such a clamp, it may not be brought back to the first position, but may directly be brought from the aforesaid third position to the aforesaid second position.
Belgian patent No. 897,288 describes presentation needles which are driven by means of levers mounted on cam wheels and which are connected on one side to the presentation needles while their other end can be held by means of connectable hook elements. These hook elements can only be engaged with the levers when the presentation needles are in their motionless position. This design has, however, the disadvantage that it is not applicable for regulation whereby, as already mentioned, the thread presentation elements arrive only for a short while at their motionless position or not at all in the case of overlapping cycles.